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Re: Question about adding old code

Posted: Fri Nov 08, 2013 3:39 am
by ExSport
From the ancient communication with Shagrath:
... Current DTS trick is wrapping it to LPCM2.0 which is limited to 1,5Mbit ...

... Yes, I tried several hours to force an audio signal higher than 48
kHz through the DLNA connection without success ...

... ps3 kept outputting 48kHz, so I concluded at the time, it blocked
audio higher frequencies in DLNA Mode ...

... DTS-HD cannot work because it needs a LPCM stream of 2 channels
sampled at 192kHz = 6.1Mbits/s. (8 channels for TrueHD, 24Mbits !!!) but PS3 limits output to 48kHz only ...

... So what about using 48kHz but more channels?...4,6Mbit (5.1 x 16bit at 48Khz) or 7.1 = 6Mbit? ...

...the way we are using the DTS trick is a via the SPDIF standard: IEC 60958 for uncompressed PCM, and IEC 61937 (hence my class IEC61937AudioOutputStream) for compressed data (ac3, dts) wrapped by a PCM stream ... But spdif is an old standard and can't go higher than 1,5Mbits (2 16bits channels in PCM at 48kHz) : http://ac3filter.net/files/docs/ac3filt ... x1-30001.1 ...
Conclusion:
Audio stream can't be bigger than 1,5Mbit including padding data + wrapped AC3/DTS/AAC.
It means DTS-HD/TrueHD is impossible and AAC only possible if external receiver supports AAC natively and size is less than 1,5Mbit.

Re: Question about adding old code

Posted: Fri Nov 08, 2013 4:05 am
by rnb5500
Yeah, that's where "HDAudioPassthrough" is something of a misnomer, but I think it was originally thought possible. I guess after figuring it wouldn't be the feature was renamed encodedAudioPassthrough but the names were used interchangeably in the code I read over.